6050번 - Mountain Watching

문제

One day, Bessie was gazing off into the distance at the beautiful Wisconsin mountains when she wondered to herself: which mountain is the widest one?

She decided to take N (1 <= N <= 100,000) equally-spaced height measurements H_i (1 <= H_i <= 1,000,000,000) sequentially along the horizon using her new Acme Long Distance Geoaltimeter.

A mountain is defined to be a consecutive sequence of H_i values which increases (or stays the same) and then decreases (or stays the same), e.g., 2, 3, 3, 5, 4, 4, 1. It is possible for a mountain on the edge of her field of vision only to increase or only to decrease in height, as well.

The width of a mountain is the number of measurements it encompasses. Help Bessie identify the widest mountain.